Paraffin-embedded Liver Sections Research Articles

MOLECULAR PATHOGENESIS OF HEPATITIS B VIRUS INFECTION: SIMULTANEOUS DETECTION OF VIRAL DNA AND ANTIGENS IN PARAFFIN-EMBEDDED LIVER SECTIONS

Hepatitis B virus (HBV) DNA and viral antigens were simultaneously identified by immunohistochemical staining of formalinfixed, paraffin-embedded liver sections followed by in situ hybridisation. In the developed radioautographs, silver grains indicate the location of viral DNA in the cell and the immunohistochemical stain marks sites of accumulation of viral antigen. In liver from a patient with chronic active hepatitis serologically positive for hepatitis B surface antigen and e antigen (HBsAg/HBeAg) viral nucleotide sequences, representing actively replicating DNA species, were demonstrated predominantly in the cytoplasm. Viral core antigen (HBcAg) was expressed in the liver cell nuclei. HBcAg was not detectable in most hepatocytes with high levels of viral replication. Conversely, most liver cells in which HBcAg was found did not contain replicating HBV. HBcAg and replicating viral DNA species were not detectable in hepatocytes undergoing pathological changes, such as ground glass cells. Because no pathological changes could be identified either in hepatocytes with high levels of HBV replication or expression of nuclear HBcAg, the liver cell damage in this patient with chronic hepatitis B was presumably induced by other mechanisms. The simultaneous observation of viral DNA, antigens, and pathological changes at the single cell level and their correlation with clinical findings should contribute to the understanding of the molecular mechanisms underlying HBV-induced liver cell injury.

Failure to detect hypnozoites in hepatic tissue containing exoerythrocytic schizonts of Plasmodium knowlesi.

Sections of paraffin-embedded rhesus liver containing numerous nearly mature exoerythrocytic schizonts of the non-relapsing malaria parasite, Plasmodium knowlesi, were examined for the presence of hypnozoites by indirect immunofluorescence, employing both homologous and strongly cross-reacting heterologous sera. No hypnozoites or evident hypnozoite equivalents were detected in tissue which, by analogy with results obtained for the relapsing species, P. cynomolgi bastianellii, should have contained 35--50 of the uninucleate forms. These observations are presented as additional evidence in favor of the hypnozoite theory of malarial relapse.

Heterogeneous staining of rat hepatocyte nuclei by HBFP technique.

The non-enzymatic histochemical technique Haematoxylin--Basic Fuchsin--picric acid (HBFP) was studied in fresh-frozen and Carnoy-fixed, paraffin-embedded rat liver sections. The hepatocyte nuclei fell into two populations and showed either a crimson red or purple staining in frozen as well as paraffin sections. The heterogeneous staining of the rat heptocyte nuclei was also present when the tissue sections were stained by Methyl Green--Pyronin stain. The differing nuclear staining was present in the isolated nuclei also. The HBFP technique, therefore, appears potentially useful when applied to liver and other tissues as well.